HP 8901B Operation And Calibration Manual page 397

Adjustments Model 8901B
0 0
V E R T I C A L
I N P U T
: : : : :
0 0 0 0 0 0
a
0000 0
D O
: ; ; ; ;
0
-
0
0 0
000000
a
0000
0
Adjustment 2
INTERNALREFERENCE FREQUENCY
Service Sheets
22
and 31
Description
An oscilloscope, triggered by an external reference, is used
to
monitor the internal reference frequency.
The internal reference frequency is adjusted for a stationary waveform on the oscilloscope.
Equipment
F'requency Standard
..........................................................
House Standard
Oscilloscope
......................................................................
HP 1740A
EXTERNAL
T R I Q Q E R
I
FREQUENCY
OUTPUT
STANDARD
OSCILLOSCOPE
(100 k H t . 1 M H t .
5
MHt.OR
10
YHZ)
NOTE:
CONNECT THE OSCILLOSCOPE'S VERTICAL INPUT TO A11J5
( I N T
10 YHZ
OUT1 I N THE
8902A
OR
THE REAR-PANEL
T I M E
BASE
10
MHt
OUTPUT ( O P T I O N
002
O N L Y ) .
Figure
5-1.
Internal Reference
frequency
Adjustment Test Setup
Procedure
1. Connect the equipment
as shown in Figure 5-1. Allow the equipment to warm up for 15
minutes. For Option 002,
a warm-up of the Modulation Analyzer of several days with covers on
is recommended.
2. Set the oscilloscope's vertical sensitivity to view the Modulation Analyzer's time base output. Set
its horizontal scale for 10
ps
per division. Set the oscilloscope
to
trigger externally.
3. Adjust AllC14 (10 MHZ REF) or, for Option
002,
Y1 (COARSE and FINE) for a stationary
waveform.
If
adjusting AllC14, use a totally non-metallic adjustment tool.
NOTE
Movement of the waueform to the right at a rate of one division per second means that the Modulation
Analyzer's
time
base
is
low by 0.1 ppm.
I f the frequency of the internal reference
is
quite far
off,
the oscilloscope display may be difficult to
interpret. I n that case, connect the frequency standard directly to the Modulation Analyzer's
INPUT,
press
FREQ,
and adjust the internal reference frequency for a display equal to the standard's frequency,
then begin again at step 2.
5-6
Adjustment 2